1. Field of the Invention
This invention relates to novel 5,6-dihydroimidazo[2,1-b]thiazole-2-carboxamide derivatives, and more specifically to 5,6-dihydroimidazo[2,1-b]thiazole-2-carboxamide derivatives having excellent immuno-modulating activities.
2. Description of the Prior Art
A number of compounds having the imidazothiazole skeleton have heretofore been synthesized. For example, an imidazo[2,1-b]thiazole derivative (levamisole) represented by the following formula: ##STR2## has been reported to have some immuno-modulating activities (German Offenlegungsschrift No. 23 40 632).
It has also been reported that certain anti-inflammatory activities are exhibited by imidazo[2,1-b]thiazole derivatives represented by the following formula: ##STR3## wherein R.sub.10 means a C.sub.1 -C.sub.3 -alkylsulfonyl or ##STR4## group, R.sub.14 and R.sub.15 being independently a hydrogen atom or a monofluorophenyl, trifluoromethylphenyl or trimethylphenyl group with a proviso that when either one of R.sub.14 and R.sub.15 is a hydrogen atom the other one is other than a hydrogen atom or being coupled to each other together with the associated nitrogen atom to form a 1-(2,3-dimethyl)pyrrolidinyl group, R.sub.11 denotes a C.sub.1 -C.sub.3 -alkyl or phenyl group, and R.sub.12 and R.sub.13 stand independently for a hydrogen atom or a C.sub.1 -C.sub.4 -alkyl group [U.S. Pat. No. 4,224,334; J. Med. Chem. 24, 604-609 (1981)]; and by 5,6-dihydroimidazo[2,1-b]-thiazole derivatives represented by the following formula: ##STR5## wherein R.sub.16 means a substituted or unsubstituted phenyl or naphthalyl group (Japanese Patent Laid-Open No. 169490/1982).